KVM: s390: implement KVM_CAP_NR/MAX_VCPUS

Let userspace know the number of max and supported cpus for kvm on s390.
Return KVM_MAX_VCPUS (currently 64) for both values.
Signed-off-by: NChristian Borntraeger <borntraeger@de.ibm.com>
Signed-off-by: NMarcelo Tosatti <mtosatti@redhat.com>

arch/s390/kvm/kvm-s390.c

@@ -136,6 +136,10 @@ int kvm_dev_ioctl_check_extension(long ext)
 	case KVM_CAP_SYNC_REGS:
 		r = 1;
 		break;
+	case KVM_CAP_NR_VCPUS:
+	case KVM_CAP_MAX_VCPUS:
+		r = KVM_MAX_VCPUS;
+		break;
 	default:
 		r = 0;
 	}